AI2-THOR-Full-Starter-Template.ipynb fails on the second cell

[xenotaur]

Hello! I wanted to test the AI2-THOR-Full-Starter-Template.ipynb and made a copy to Drive as suggested, but the notebook fails on its second cell and there's no obvious documentation on why it did. The fail point is the cell containing:

controller = Controller()

which seems to not be able to find an X server even though the prior cell creates one with the line:

ai2thor_colab.start_xserver()

I have looked online to see if there's a indication of which Colab runtime to use, but there isn't anything. This makes me think that the instructions that say that you can use an online runtime are now out of date, and that you can only use it with a local runtime - or that there are missing instructions in the colab (perhaps found somewhere else which could be linked in?) that would help set up the runtime correctly.

Detailed error messages follow:

The previous (first) cell's output is:

---------------------------------------------------------------------------
# Stuff deleted
ai2thor_colab.start_xserver()
---------------------------------------------------------------------------
WARNING:py.warnings:/usr/local/lib/python3.10/dist-packages/moviepy/video/io/sliders.py:61: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if event.key is 'enter':
AI2-THOR Version: 5.0.0
---------------------------------------------------------------------------

The failing (second) cell's output is:

---------------------------------------------------------------------------
controller = Controller()
---------------------------------------------------------------------------
Exception                                 Traceback (most recent call last)
[<ipython-input-2-de96efd4658a>](https://localhost:8080/#) in <cell line: 1>()
----> 1 controller = Controller()

1 frames
[/usr/local/lib/python3.10/dist-packages/ai2thor/controller.py](https://localhost:8080/#) in find_build(self, local_build, commit_id, branch, platform)
   1350                 message += instructions
   1351             error_messages.append(message)
-> 1352         raise Exception("\n".join(error_messages))
   1353 
   1354     def find_platform_builds(

Exception: The following builds were found, but had missing dependencies. Only one valid platform is required to run AI2-THOR.
Platform Linux64 failed validation with the following errors: Invalid display: :1. Failed to connect Can't connect to display ":1": [Errno 111] Connection refused 
  Linux64 requires a X11 server to be running with GLX. If you have a NVIDIA GPU, please run: sudo ai2thor-xorg start
---------------------------------------------------------------------------

Note the first time that it failed, the error was slightly different (note I have reconnected to the kernel in the above):

---------------------------------------------------------------------------
Exception                                 Traceback (most recent call last)
[<ipython-input-8-de96efd4658a>](https://localhost:8080/#) in <cell line: 1>()
----> 1 controller = Controller()

1 frames
[/usr/local/lib/python3.10/dist-packages/ai2thor/controller.py](https://localhost:8080/#) in __init__(self, quality, fullscreen, headless, port, start_unity, local_executable_path, local_build, commit_id, branch, width, height, x_display, host, scene, image_dir, save_image_per_frame, depth_format, add_depth_noise, download_only, include_private_scenes, server_class, gpu_device, platform, server_timeout, server_start_timeout, **unity_initialization_parameters)
    511             self._build = ai2thor.build.ExternalBuild(local_executable_path)
    512         else:
--> 513             self._build = self.find_build(local_build, commit_id, branch, platform)
    514 
    515         self._build.download()

[/usr/local/lib/python3.10/dist-packages/ai2thor/controller.py](https://localhost:8080/#) in find_build(self, local_build, commit_id, branch, platform)
   1350                 message += instructions
   1351             error_messages.append(message)
-> 1352         raise Exception("\n".join(error_messages))
   1353 
   1354     def find_platform_builds(

Exception: The following builds were found, but had missing dependencies. Only one valid platform is required to run AI2-THOR.
Platform Linux64 failed validation with the following errors: Invalid display: :1. Failed to connect Can't connect to display ":1": [Errno 111] Connection refused 
  Linux64 requires a X11 server to be running with GLX. If you have a NVIDIA GPU, please run: sudo ai2thor-xorg start
  ---------------------------------------------------------------------------